1. Field of the Invention
This invention is directed to electrical switching apparatus and, more particularly, to circuit interrupters, such as a circuit breakers, which employ closing mechanisms.
2. Background Information
Electrical switching apparatus include, for example, circuit switching devices and circuit interrupters, such as circuit breakers, network protectors, disconnects and transfer switches. Circuit breakers are generally old and well known in the art. An example of a circuit breaker is disclosed in U.S. Pat. No. 5,341,191. Circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition.
Molded case circuit breakers include a pair of separable contacts per phase which may be operated either manually by way of a handle disposed on the outside of the case or automatically in response to an overcurrent condition. Typically, such circuit breakers include an operating mechanism, which is designed to rapidly open and close the separable contacts, and a trip mechanism, which senses overcurrent conditions in an automatic mode of operation. Upon sensing an overcurrent condition, the trip mechanism trips the operating mechanism to a trip state which moves the separable contacts to their open position.
Some trip mechanisms employ a microprocessor to detect various types of overcurrent trip conditions, such as, for example, a long delay trip, a short delay trip, an instantaneous trip, or a ground fault trip. Other trip mechanisms detect a wide variety of trip conditions and alarm conditions based on line voltage, frequency, phasing or power.
It is known to receive a remotely generated command from a communication network to close the circuit interrupter's separable contacts. It is also known to employ a remote contact or push button to provide a remote command to close the separable contacts. The microprocessor of the circuit interrupter employs the remote close command, along with a signal which confirms the open state of the separable contacts, and produces a close signal which energizes a close actuator, such as a close relay. The close relay, in turn, drives the operating mechanism to close the separable contacts. See, for example, U.S. Pat. No. 4,751,606.
In some circuit interrupters, the trip mechanism employs a trip actuator, such as a shunt trip coil, which is energized and latched in response to a trip condition. Then, in order to close the separable contacts, the user must locally reset the circuit interrupter to deenergize and unlatch the shunt trip coil.
As this requires that a user must locally reset the circuit interrupter before the remote close command is issued, there is room for improvement in electrical switching apparatus which employ closing mechanisms.